1. Field of the Invention
The present invention relates to a polarization illuminating device for uniformly illuminating a rectangular illumination region or the like by using polarized lights whose directions of polarization are aligned, and to a projection type display device using this polarization illuminating device. More specifically, the present invention relates to a structure for synthesizing lights emitted from two light source sections while aligning the directions of polarization thereof.
2. Description of Related Art
In a liquid crystal display device using a modulator of a type which modulates a particular polarized light like a liquid crystal element, only one of two polarization components emitted from the light source can be utilized. Thus, to obtain a bright projection image, it is necessary to enhance the efficiency in the utilization of light. However, there is a limitation in enhancing the efficiency in the utilization of light in a projection type display device using only one light source. Thus, using a plurality of light sources to augment the quantity of light is a means for obtaining a bright projection image.
However, simply arranging a plurality of light sources only results in the area of the light source images being correspondingly augmented, and the quantity of light per fixed area is the same as when only one light source is used. Thus, in this case, there is substantially no increase in quantity of light per fixed area even though a plurality of light sources are used.
Even when the quantity of light is augmented by using a plurality of light sources, if only one of the two polarization components of the light emitted from the light source can be utilized, the rest of the quantity of light is wasted, and half the effectiveness is lost.